The class String includes methods for examining individual characters of the sequence, for comparing strings, for searching strings, for extracting substrings, and for creating a copy of a string with all characters translated to uppercase or to lowercase.
Case mapping is based on the Unicode Standard version specified by the
Character
class.
Case mapping relies heavily on the information provided by the Unicode Consortium's Unicode 3.0 specification. The specification's UnicodeData.txt and SpecialCasing.txt files are used extensively to provide case mapping.

The Java language provides special support for the string concatenation operator ( + ), and for conversion of other objects to strings. String concatenation is implemented through the StringBuffer class and its append method. String conversions are implemented through the method toString, defined by Object and inherited by all classes in Java. For additional information on string concatenation and conversion, see Gosling, Joy, and Steele,
The Java Language Specification
.

Unless otherwise noted, passing a
null
argument to a constructor or method in this class will cause a
NullPointerException
to be thrown.

A String represents a string in the UTF-16 format in which supplementary characters are represented by surrogate pairs (see the section
Unicode Character Representations
in the Character class for more information). Index values refer to char code units, so a supplementary character uses two positions in a String.

The String class provides methods for dealing with Unicode code points (i.e., characters), in addition to those for dealing with Unicode code units (i.e., char values).

String
()
Initializes a newly created String object so that it represents an empty character sequence.

String
(byte[] bytes)
Constructs a new
String
by decoding the specified array of bytes using the platform's default charset.

String
(byte[] ascii, int hibyte)
Deprecated.
This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a charset name or that use the platform's default charset.

String
(byte[] bytes, int offset, int length)
Constructs a new
String
by decoding the specified subarray of bytes using the platform's default charset.

String
(byte[] ascii, int hibyte, int offset, int count)
Deprecated.
This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a charset name or that use the platform's default charset.

String
(byte[] bytes,
String
charsetName)
Constructs a new
String
by decoding the specified array of bytes using the specified charset.

String
(char[] value)
Allocates a new String so that it represents the sequence of characters currently contained in the character array argument.

String
(char[] value, int offset, int count)
Allocates a new String that contains characters from a subarray of the character array argument.

String
(int[] codePoints, int offset, int count)
Allocates a new String that contains characters from a subarray of the Unicode code point array argument.

String
(
String
original)
Initializes a newly created String object so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string.

String
(
StringBuffer
buffer)
Allocates a new string that contains the sequence of characters currently contained in the string buffer argument.

String
(
StringBuilder
Allocates a new string that contains the sequence of characters currently contained in the string builder argument.

Method Summary

char

charAt
(int index)
Returns the
char value
character
at the specified index.

int

codePointAt
(int index)
Returns the character (Unicode code point) at the specified index.

getBytes
()
Encodes this
String
into a sequence of bytes using the platform's default charset, storing the result into a new byte array.

void

getBytes
(int srcBegin, int srcEnd, byte[] dst, int dstBegin)
Deprecated.
This method does not properly convert characters into bytes. As of JDK 1.1, the preferred way to do this is via the the getBytes() method, which uses the platform's default charset.

byte[]

getBytes
(
String
charsetName)
Encodes this
String
into a sequence of bytes using the named charset, storing the result into a new byte array.

CASE_INSENSITIVE_ORDER

A Comparator that orders String objects as by compareToIgnoreCase. This comparator is serializable.

Note that this Comparator does not take locale into account, and will result in an unsatisfactory ordering for certain locales. The java.text package provides Collators to allow locale-sensitive ordering.

String

Initializes a newly created String object so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string. Unless an explicit copy of original is needed, use of this constructor is unnecessary since Strings are immutable.

Parameters:

original - a String.

String

public String(char[] value)

Allocates a new String so that it represents the sequence of characters currently contained in the character array argument. The contents of the character array are copied; subsequent modification of the character array does not affect the newly created string.

Parameters:

value - the initial value of the string.

String

public String(char[] value,
int offset,
int count)

Allocates a new String that contains characters from a subarray of the character array argument. The offset argument is the index of the first character of the subarray and the count argument specifies the length of the subarray. The contents of the subarray are copied; subsequent modification of the character array does not affect the newly created string.

Parameters:

value - array that is the source of characters.

offset - the initial offset.

count - the length.

Throws:

IndexOutOfBoundsException
- if the offset and count arguments index characters outside the bounds of the value array.

String

public String (int[] codePoints,
int offset,
int count)

Allocates a new String that contains characters from a subarray of the Unicode code point array argument. The offset argument is the index of the first code point of the subarray and the count argument specifies the length of the subarray. The contents of the subarray are converted to chars; subsequent modification of the int array does not affect the newly created string.

IndexOutOfBoundsException
- if the offset and count arguments index characters outside the bounds of the codePoints array.

Since:

1.5

String

public String(byte[] ascii,
int hibyte,
int offset,
int count)

Deprecated.
This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a charset name or that use the platform's default charset.

Allocates a new String constructed from a subarray of an array of 8-bit integer values.

The offset argument is the index of the first byte of the subarray, and the count argument specifies the length of the subarray.

Each byte in the subarray is converted to a char as specified in the method above.

Parameters:

ascii - the bytes to be converted to characters.

hibyte - the top 8 bits of each 16-bit Unicode character.

offset - the initial offset.

count - the length.

Throws:

IndexOutOfBoundsException
- if the offset or count argument is invalid.

String

public String(byte[] ascii,
int hibyte)

Deprecated.
This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a charset name or that use the platform's default charset.

Allocates a new String containing characters constructed from an array of 8-bit integer values. Each character
c
in the resulting string is constructed from the corresponding component
b
in the byte array such that:

String

Constructs a new
String
by decoding the specified subarray of bytes using the specified charset. The length of the new
String
is a function of the charset, and hence may not be equal to the length of the subarray.

The behavior of this constructor when the given bytes are not valid in the given charset is unspecified. The
CharsetDecoder
class should be used when more control over the decoding process is required.

String

Constructs a new
String
by decoding the specified array of bytes using the specified charset. The length of the new
String
is a function of the charset, and hence may not be equal to the length of the byte array.

The behavior of this constructor when the given bytes are not valid in the given charset is unspecified. The
CharsetDecoder
class should be used when more control over the decoding process is required.

String

public String(byte[] bytes,
int offset,
int length)

Constructs a new
String
by decoding the specified subarray of bytes using the platform's default charset. The length of the new
String
is a function of the charset, and hence may not be equal to the length of the subarray.

The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. The
CharsetDecoder
class should be used when more control over the decoding process is required.

Parameters:

bytes - the bytes to be decoded into characters

offset - the index of the first byte to decode

length - the number of bytes to decode

Throws:

IndexOutOfBoundsException
- if the offset and the length arguments index characters outside the bounds of the bytes array

Since:

JDK1.1

String

public String(byte[] bytes)

Constructs a new
String
by decoding the specified array of bytes using the platform's default charset. The length of the new
String
is a function of the charset, and hence may not be equal to the length of the byte array.

The behavior of this constructor when the given bytes are not valid in the default charset is unspecified. The
CharsetDecoder
class should be used when more control over the decoding process is required.

Parameters:

bytes - the bytes to be decoded into characters

Since:

JDK1.1

String

Allocates a new string that contains the sequence of characters currently contained in the string buffer argument. The contents of the string buffer are copied; subsequent modification of the string buffer does not affect the newly created string.

Parameters:

buffer - a StringBuffer.

String

Allocates a new string that contains the sequence of characters currently contained in the string builder argument. The contents of the string builder are copied; subsequent modification of the string builder does not affect the newly created string.

This constructor is provided to ease migration to StringBuilder. Obtaining a string from a string builder via the toString method is likely to run faster and is generally preferred.

Parameters:

sb - a StringBuilder

Since:

1.5

Method Detail

length

public int length()

Returns the length of this string. The length is equal to the number of 16-bit Unicode characters in the string.

charAt

public char charAt(int index)

Returns the
char value
character
at the specified index. An index ranges from 0 to length() - 1. The first
char value
character
of the sequence is at index 0, the next at index 1, and so on, as for array indexing.

If the char value specified by the index is a
surrogate
, the surrogate value is returned.

the
char value
character
at the specified index of this string. The first
char value
character
is at index 0.

Throws:

IndexOutOfBoundsException
- if the index argument is negative or not less than the length of this string.

codePointAt

public int codePointAt (int index)

Returns the character (Unicode code point) at the specified index. The index refers to char values (Unicode code units) and ranges from 0 to
length()
- 1.

If the char value specified at the given index is in the high-surrogate range, the following index is less than the length of this String, and the char value at the following index is in the low-surrogate range, then the supplementary code point corresponding to this surrogate pair is returned. Otherwise, the char value at the given index is returned.

Parameters:

index - the index to the char values

Returns:

the code point value of the character at the index

Throws:

IndexOutOfBoundsException
- if the index argument is negative or not less than the length of this string.

Since:

1.5

codePointBefore

public int codePointBefore (int index)

Returns the character (Unicode code point) before the specified index. The index refers to char values (Unicode code units) and ranges from 1 to
length
.

If the char value at (index - 1) is in the low-surrogate range, (index - 2) is not negative, and the char value at (index - 2) is in the high-surrogate range, then the supplementary code point value of the surrogate pair is returned. If the char value at index - 1 is an unpaired low-surrogate or a high-surrogate, the surrogate value is returned.

Parameters:

index - the index following the code point that should be returned

Returns:

the Unicode code point value before the given index.

Throws:

IndexOutOfBoundsException
- if the index argument is less than 1 or greater than the length of this string.

Since:

1.5

getChars

Copies characters from this string into the destination character array.

The first character to be copied is at index srcBegin; the last character to be copied is at index srcEnd-1 (thus the total number of characters to be copied is srcEnd-srcBegin). The characters are copied into the subarray of dst starting at index dstBegin and ending at index:

getBytes

Deprecated.
This method does not properly convert characters into bytes. As of JDK 1.1, the preferred way to do this is via the the getBytes() method, which uses the platform's default charset.

Copies characters from this string into the destination byte array. Each byte receives the 8 low-order bits of the corresponding character. The eight high-order bits of each character are not copied and do not participate in the transfer in any way.

The first character to be copied is at index srcBegin; the last character to be copied is at index srcEnd-1. The total number of characters to be copied is srcEnd-srcBegin. The characters, converted to bytes, are copied into the subarray of dst starting at index dstBegin and ending at index:

equalsIgnoreCase

Compares this String to another String, ignoring case considerations. Two strings are considered equal ignoring case if they are of the same length, and corresponding characters in the two strings are equal ignoring case.

Two characters c1 and c2 are considered the same, ignoring case if at least one of the following is true:

compareTo

Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings. The character sequence represented by this String object is compared lexicographically to the character sequence represented by the argument string. The result is a negative integer if this String object lexicographically precedes the argument string. The result is a positive integer if this String object lexicographically follows the argument string. The result is zero if the strings are equal; compareTo returns 0 exactly when the
equals(Object)
method would return true.

This is the definition of lexicographic ordering. If two strings are different, then either they have different characters at some index that is a valid index for both strings, or their lengths are different, or both. If they have different characters at one or more index positions, let
k
be the smallest such index; then the string whose character at position
k
has the smaller value, as determined by using the < operator, lexicographically precedes the other string. In this case, compareTo returns the difference of the two character values at position k in the two string -- that is, the value:

this.charAt(k)-anotherString.charAt(k)

If there is no index position at which they differ, then the shorter string lexicographically precedes the longer string. In this case, compareTo returns the difference of the lengths of the strings -- that is, the value:

this.length()-anotherString.length()

Parameters:

anotherString - the String to be compared.

Returns:

the value 0 if the argument string is equal to this string; a value less than 0 if this string is lexicographically less than the string argument; and a value greater than 0 if this string is lexicographically greater than the string argument.

compareTo

Compares this String to another Object. If the Object is a String, this function behaves like compareTo(String). Otherwise, it throws a ClassCastException (as Strings are comparable only to other Strings).

the value 0 if the argument is a string lexicographically equal to this string; a value less than 0 if the argument is a string lexicographically greater than this string; and a value greater than 0 if the argument is a string lexicographically less than this string.

compareToIgnoreCase

Compares two strings lexicographically, ignoring case differences. This method returns an integer whose sign is that of calling compareTo with normalized versions of the strings where case differences have been eliminated by calling Character.toLowerCase(Character.toUpperCase(character)) on each character.

Note that this method does not take locale into account, and will result in an unsatisfactory ordering for certain locales. The java.text package provides collators to allow locale-sensitive ordering.

Parameters:

str - the String to be compared.

Returns:

a negative integer, zero, or a positive integer as the the specified String is greater than, equal to, or less than this String, ignoring case considerations.

regionMatches

A substring of this
String
object is compared to a substring of the argument other. The result is true if these substrings represent identical character sequences. The substring of this
String
object to be compared begins at index
toffset
and has length
len
. The substring of other to be compared begins at index
ooffset
and has length
len
. The result is
false
if and only if at least one of the following is true:

toffset
is negative.

ooffset
is negative.

toffset+len
is greater than the length of this
String
object.

ooffset+len
is greater than the length of the other argument.

There is some nonnegative integer
k
less than
len
such that:
this.charAt(toffset+
k
) != other.charAt(ooffset+
k
)

Parameters:

toffset - the starting offset of the subregion in this string.

other - the string argument.

ooffset - the starting offset of the subregion in the string argument.

len - the number of characters to compare.

Returns:

true if the specified subregion of this string exactly matches the specified subregion of the string argument; false otherwise.

regionMatches

A substring of this
String
object is compared to a substring of the argument
other
. The result is
true
if these substrings represent character sequences that are the same, ignoring case if and only if
ignoreCase
is true. The substring of this
String
object to be compared begins at index
toffset
and has length
len
. The substring of
other
to be compared begins at index
ooffset
and has length
len
. The result is
false
if and only if at least one of the following is true:

toffset
is negative.

ooffset
is negative.

toffset+len
is greater than the length of this
String
object.

ooffset+len
is greater than the length of the other argument.

ignoreCase
is
false
and there is some nonnegative integer
k
less than
len
such that:

this.charAt(toffset+k) != other.charAt(ooffset+k)

ignoreCase
is
true
and there is some nonnegative integer
k
less than
len
such that:

ooffset - the starting offset of the subregion in the string argument.

len - the number of characters to compare.

Returns:

true if the specified subregion of this string matches the specified subregion of the string argument; false otherwise. Whether the matching is exact or case insensitive depends on the ignoreCase argument.

startsWith

Tests if this string starts with the specified prefix beginning a specified index.

Parameters:

prefix - the prefix.

toffset - where to begin looking in the string.

Returns:

true if the character sequence represented by the argument is a prefix of the substring of this object starting at index toffset; false otherwise. The result is false if toffset is negative or greater than the length of this String object; otherwise the result is the same as the result of the expression

startsWith

true if the character sequence represented by the argument is a prefix of the character sequence represented by this string; false otherwise. Note also that true will be returned if the argument is an empty string or is equal to this String object as determined by the
equals(Object)
method.

Since:

1. 0

endsWith

true if the character sequence represented by the argument is a suffix of the character sequence represented by this object; false otherwise. Note that the result will be true if the argument is the empty string or is equal to this String object as determined by the
equals(Object)
method.

hashCode

public int hashCode()

Returns a hash code for this string. The hash code for a String object is computed as

s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]

using int arithmetic, where s[i] is the
i
th character of the string, n is the length of the string, and ^ indicates exponentiation. (The hash value of the empty string is zero.)

indexOf

public int indexOf(int ch)

Returns the index within this string of the first occurrence of the specified character. If a character with value ch occurs in the character sequence represented by this String object, then the index
(in Unicode code units)
of the first such occurrence is
returned. For values of ch in
returned -- that is,
the
range from 0 to 0xFFFF (inclusive), this is the
smallest value
k
such that:

this.charAt(k) == ch

is true.
For other values of ch, it is the smallest value
k
such that:

this.codePointAt( k ) == ch

is true. In either case, if no such character occurs in this string, then -1 is returned.
If no such character occurs in this string, then -1 is returned.

Parameters:

ch - a
character (Unicode code point).
character.

Returns:

the index of the first occurrence of the character in the character sequence represented by this object, or -1 if the character does not occur.

indexOf

public int indexOf(int ch,
int fromIndex)

Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.

If a character with value ch occurs in the character sequence represented by this String object at an index no smaller than fromIndex, then the index of the first such occurrence is
returned. For values of ch in
returned--that is,
the
range from 0 to 0xFFFF (inclusive), this is the
smallest value
k
such that:

(this.charAt(k) == ch) && (k >= fromIndex)

is true.
For other values of ch, it is the smallest value
k
such that:

(this.codePointAt( k ) == ch) && ( k >= fromIndex)

is true. In either case, if no such character occurs in this string at or after position fromIndex, then -1 is returned.
If no such character occurs in this string at or after position fromIndex, then -1 is returned.

There is no restriction on the value of fromIndex. If it is negative, it has the same effect as if it were zero: this entire string may be searched. If it is greater than the length of this string, it has the same effect as if it were equal to the length of this string: -1 is returned.

All indices are specified in char values (Unicode code units).

Parameters:

ch - a
character (Unicode code point).
character.

fromIndex - the index to start the search from.

Returns:

the index of the first occurrence of the character in the character sequence represented by this object that is greater than or equal to fromIndex, or -1 if the character does not occur.

lastIndexOf

public int lastIndexOf(int ch)

Returns the index within this string of the last occurrence of the specified character.
For values of ch in the range from 0 to 0xFFFF (inclusive), the index (in Unicode code units) returned is the largest value
That is, the index returned is the largest value
k
such that:

this.charAt(k) == ch

is true.
For other values of ch, it is the largest value
k
such that:

this.codePointAt( k ) == ch

is true. In either case, if no such character occurs in this string, then -1 is returned.
The String is searched backwards starting at the last character.

Parameters:

ch - a
character (Unicode code point).
character.

Returns:

the index of the last occurrence of the character in the character sequence represented by this object, or -1 if the character does not occur.

lastIndexOf

public int lastIndexOf(int ch,
int fromIndex)

Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index.
For values of ch in
That is,
the
range from 0 to 0xFFFF (inclusive), the
index returned is the largest value
k
such that:

(this.charAt( k ) this.charAt(k) == ch) && ( k (k <= fromIndex)

is true.
For other values of ch, it is the largest value
k
such that:

(this.codePointAt( k ) == ch) && ( k <= fromIndex)

is true. In either case, if no such character occurs in this string at or before position fromIndex, then -1 is returned.

All indices are specified in char values (Unicode code units).

Parameters:

ch - a
character (Unicode code point).
character.

fromIndex - the index to start the search from. There is no restriction on the value of fromIndex. If it is greater than or equal to the length of this string, it has the same effect as if it were equal to one less than the length of this string: this entire string may be searched. If it is negative, it has the same effect as if it were -1: -1 is returned.

Returns:

the index of the last occurrence of the character in the character sequence represented by this object that is less than or equal to fromIndex, or -1 if the character does not occur before that point.

lastIndexOf

Returns the index within this string of the rightmost occurrence of the specified substring. The rightmost empty string "" is considered to occur at the index value this.length(). The returned index is the largest value
k
such that

this.startsWith(str, k)

is true.

Parameters:

str - the substring to search for.

Returns:

if the string argument occurs one or more times as a substring within this object, then the index of the first character of the last such substring is returned. If it does not occur as a substring, -1 is returned.

substring

Returns a new string that is a substring of this string. The substring begins at the specified beginIndex and extends to the character at index endIndex - 1. Thus the length of the substring is endIndex-beginIndex.

concat

If the length of the argument string is 0, then this String object is returned. Otherwise, a new String object is created, representing a character sequence that is the concatenation of the character sequence represented by this String object and the character sequence represented by the argument string.

replace

Returns a new string resulting from replacing all occurrences of oldChar in this string with newChar.

If the character oldChar does not occur in the character sequence represented by this String object, then a reference to this String object is returned. Otherwise, a new String object is created that represents a character sequence identical to the character sequence represented by this String object, except that every occurrence of oldChar is replaced by an occurrence of newChar.

Examples:

"mesquite in your cellar".replace('e', 'o')
returns "mosquito in your collar"
"the war of baronets".replace('r', 'y')
returns "the way of bayonets"
"sparring with a purple porpoise".replace('p', 't')
returns "starring with a turtle tortoise"
"JonL".replace('q', 'x') returns "JonL" (no change)

Parameters:

oldChar - the old character.

newChar - the new character.

Returns:

a string derived from this string by replacing every occurrence of oldChar with newChar.

replace

Replaces each substring of this string that matches the literal target string with the specified literal replacement string. The replacement proceeds from the beginning of the string to the end, for example, replacing "aa" with "b" in the string "aaa" will result in "ba" rather than "ab".

Parameters:

target - The string to be replaced

replacement - The replacement string

Returns:

The resulting string

Throws:

NullPointerException
- if target or replacement is null.

Since:

1.5

split

The array returned by this method contains each substring of this string that is terminated by another substring that matches the given expression or is terminated by the end of the string. The substrings in the array are in the order in which they occur in this string. If the expression does not match any part of the input then the resulting array has just one element, namely this string.

The
limit
parameter controls the number of times the pattern is applied and therefore affects the length of the resulting array. If the limit
n
is greater than zero then the pattern will be applied at most
n
- 1 times, the array's length will be no greater than
n
, and the array's last entry will contain all input beyond the last matched delimiter. If
n
is non-positive then the pattern will be applied as many times as possible and the array can have any length. If
n
is zero then the pattern will be applied as many times as possible, the array can have any length, and trailing empty strings will be discarded.

The string
"boo:and:foo"
, for example, yields the following results with these parameters:

Regex

Limit

Result

:

2

{ "boo", "and:foo" }

:

5

{ "boo", "and", "foo" }

:

-2

{ "boo", "and", "foo" }

o

5

{ "b", "", ":and:f", "", "" }

o

-2

{ "b", "", ":and:f", "", "" }

o

0

{ "b", "", ":and:f" }

An invocation of this method of the form
str.
split(
regex
,
n
)
yields the same result as the expression

toLowerCase

Converts all of the characters in this String to lower case using the rules of the given Locale. Case
mapping is based
mappings rely heavily
on the Unicode
Standard version specified by the
Character
class.
specification's character data.
Since case mappings are not always 1:1 char mappings, the resulting String may be a different length than the original String.

toUpperCase

Converts all of the characters in this String to upper case using the rules of the given Locale. Case
mapping is based
mappings rely heavily
on the Unicode
Standard version specified by the
Character
class.
specification's character data.
Since case mappings are not always 1:1 char mappings, the resulting String may be a different length than the original String.

Examples of locale-sensitive and 1:M case mappings are in the following table.

trim

Returns a copy of the string, with leading and trailing whitespace omitted.

If this String object represents an empty character sequence, or the first and last characters of character sequence represented by this String object both have codes greater than '\u0020' (the space character), then a reference to this String object is returned.

Otherwise, if there is no character with a code greater than '\u0020' in the string, then a new String object representing an empty string is created and returned.

Otherwise, let
k
be the index of the first character in the string whose code is greater than '\u0020', and let
m
be the index of the last character in the string whose code is greater than '\u0020'. A new String object is created, representing the substring of this string that begins with the character at index
k
and ends with the character at index
m
-that is, the result of this.substring(
k
,
m
+1).

This method may be used to trim
whitespace
from the beginning and end of a string; in fact, it trims all ASCII control characters as well.

Returns:

A copy of this string with leading and trailing white space removed, or this string if it has no leading or trailing white space.

args - Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by the
Java Virtual Machine Specification
. The behaviour on a
null
argument depends on the
conversion
.

Returns:

A formatted string

Throws:

IllegalFormatException - If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the
Details
section of the formatter class specification.

args - Arguments referenced by the format specifiers in the format string. If there are more arguments than format specifiers, the extra arguments are ignored. The number of arguments is variable and may be zero. The maximum number of arguments is limited by the maximum dimension of a Java array as defined by the
Java Virtual Machine Specification
. The behaviour on a
null
argument depends on the
conversion
.

Returns:

A formatted string

Throws:

IllegalFormatException - If a format string contains an illegal syntax, a format specifier that is incompatible with the given arguments, insufficient arguments given the format string, or other illegal conditions. For specification of all possible formatting errors, see the
Details
section of the formatter class specification

valueOf

Returns the string representation of a specific subarray of the char array argument.

The offset argument is the index of the first character of the subarray. The count argument specifies the length of the subarray. The contents of the subarray are copied; subsequent modification of the character array does not affect the newly created string.

Parameters:

data - the character array.

offset - the initial offset into the value of the String.

count - the length of the value of the String.

Returns:

a string representing the sequence of characters contained in the subarray of the character array argument.

Throws:

IndexOutOfBoundsException
- if offset is negative, or count is negative, or offset+count is larger than data.length.

intern

A pool of strings, initially empty, is maintained privately by the class String.

When the intern method is invoked, if the pool already contains a string equal to this String object as determined by the
equals(Object)
method, then the string from the pool is returned. Otherwise, this String object is added to the pool and a reference to this String object is returned.

It follows that for any two strings s and t, s.intern() == t.intern() is true if and only if s.equals(t) is true.

All literal strings and string-valued constant expressions are interned. String literals are defined in §3.10.5 of the
Java Language Specification

Returns:

a string that has the same contents as this string, but is guaranteed to be from a pool of unique strings.